Error handling in a geometric correction engine

ABSTRACT

A method for error handling in a geometric correction engine (GCE) is provided that includes receiving configuration parameters by the GCE, generating, by the GCE in accordance with the configuration parameters, output blocks of an output frame based on corresponding blocks of an input frame, detecting, by the GCE, a run-time error during the generating, and reporting, by the GCE, an event corresponding to the run-time error.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent ApplicationNo. 62/956,377 filed Jan. 2, 2020, which is incorporated herein byreference in its entirety.

BACKGROUND

Cameras with wide angle lens, e.g., fisheye cameras, are being used inan increasing number of applications such as surveillance, roboticvision, automotive rear-view imaging systems, automotive surround viewimaging systems, etc. to provide a 180+° field of view. While suchlenses provide very large wide-angle views, the images produced may beseverely distorted when the hemispherical scene is projected onto a flatsurface for viewing. Therefore, the images captured by such cameras arecorrected to approximately rectilinear versions before being presentedto viewers. In real-time applications, a geometric correction engine(GCE) may be included in a video processing accelerator in asystem-on-a-chip (SoC) to perform geometric image transforms on imagesfrom such wide angle lenses to correct the distortion. The GCE may alsoperform image perspective changes and stereo rectification.

SUMMARY

Embodiments of the present disclosure relate to error handling in ageometric correction engine (GCE). In one aspect, a method for errorhandling in a geometric correction engine (GCE) is provided thatincludes receiving configuration parameters by the GCE, generating, bythe GCE in accordance with the configuration parameters, output blocksof an output frame based on corresponding blocks of an input frame,detecting, by the GCE, a run-time error during the generating, andreporting, by the GCE, an event corresponding to the run-time error.

In one aspect, a system-on-a-chip (SoC) is provided that includes ageometric correction engine (GCE) configured to receive configurationparameters from a user supplied control program, generate, in accordancewith the configuration parameters, output blocks of an output framebased on corresponding input blocks of an input frame, detect a run-timeerror while generating the output blocks, and report an eventcorresponding to the run-time error to the user supplied controlprogram, a memory configured to store software instructions implementingthe user supplied control program for the GCE, and at least oneprocessor coupled to the memory to execute the software instructions.

In one aspect, a geometric correction engine (GCE) is provided thatincludes a transform component configured to apply a perspectivetransform to coordinates of corners of an output block of an outputframe to generate first perspective warped coordinates, computecoordinates of corners of a mesh look-up table (LUT) block in a mesh LUTusing the first perspective warped coordinates, wherein the mesh LUTblock corresponds to the output block, and detect and report a firstrun-time error when a size of the mesh LUT block is larger than internalstorage allocated for a mesh LUT block, and a back mapping componentconfigured to back map the first perspective warped coordinates tocoordinates in an input frame using the mesh LUT block, compute abounding box for an input frame block corresponding to the output blockbased on the coordinates in the input frame, and detect and report asecond run-time error when a size of the input frame block is largerthan internal storage of the GCE allocated for an input frame block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the general operation of a geometric correctionengine (GEC);

FIGS. 2A-2C are examples of artifacts in output images when run-timeerrors occur in a GCE;

FIG. 3 is a block diagram illustrating an example of a video processingaccelerator (VPAC) incorporating a GCE;

FIG. 4 is a block diagram of an example GCE;

FIG. 5 is an example illustrating division of an output frame into nineregions in which each region has a different block size;

FIG. 6 is an example illustrating the operation of the GCE of FIG. 4 ;

FIG. 7 is an example illustrating a bounding block for fetching meshdata;

FIG. 8 is a flow diagram of a method for error handling in a GCE; and

FIG. 9 is a high level block diagram of an example multiprocessor systemon a chip (SoC).

DETAILED DESCRIPTION

Specific embodiments of the disclosure are described herein in detailwith reference to the accompanying figures. Like elements in the variousfigures are denoted by like reference numerals for consistency.

FIG. 1 illustrates the general operation of a geometric correctionengine (GEC) 104 in accordance with embodiments of the disclosure. Tocorrect a distorted image, the GEC 104 uses a technique referred to as“back mapping” in which coordinates of the pixels in the distorted inputimage are determined as a function of coordinates of pixels in theundistorted output image. Correction involves back mapping each outputpixel location to a pixel location in an input distorted image.

The GCE 104 operates on an input image block by block. An output framebuffer 102 is divided into blocks and each output block is back mappedby the GCE 104 to a block of an input frame in an input frame buffer 101using a mesh lookup table (LUT) 107 that provides a mapping of pixellocations in an output image to corresponding locations in an inputimage. For example, the GCE 104 performs perspective warping on thecoordinates of the four corners of an output block 103 and used thewarped coordinates to locate a corresponding block 106 in the mesh table107. The GCE 104 then calculates the coordinates of the corners of theinput block 105 to be used to generate the output block 103 by applyingback mapping on the perspective warped corner pixel coordinates of theoutput block 103 using the mesh table block 106. The input block 105 isfetched from the input frame buffer 101 and the GCE 104 generates theoutput image block 103 using the input image block 105.

A GCE such as the GCE 104 has several configuration parameters thevalues of which a user may determine offline by simulation. The GCE mayhave run-time errors due to issues such as limited internal memory,limited precision of integer arithmetic in the GCE, and/or unsafe oraggressive user supplied configuration parameters for the GCE. The GCEmay produce artifacts in output images when run-time errors occur. Forexample, as illustrated in FIG. 2A, the limited precision of integerarithmetic can affect the calculation of the coordinates of the desiredblock of the input image such that some of the needed pixels are not inthe fetched input image block. In another example, shown in FIG. 2B,aggressive setting of a parameter by a user results in verticalartifacts in the output image. In another example, shown in FIG. 2C, thesize of the output block, as set by user parameters, exceeds the size ofthe internal memory, resulting in horizontal artifacts in the outputimage.

Users prefer to use more aggressive GCE parameters to save memorybandwidth without worrying about output image artifacts at run time.Further, users want to allow changes to GCE parameters in real time andto be able to determine quickly if the parameter changes are safe, e.g.,to allow the angle of view in an automotive surround view system to bechanged dynamically by a driver or to provide real time calibration ofcameras in an automotive surround view system. Prior art implementationsof GCEs have not provided for graceful error handling and concealment ofthe impact of errors, i.e., artifact concealment.

Embodiments of the disclosure provide for reporting of run-time errorsin a GCE due to issues such as aggressive parameter values, dynamicchanges in parameter values due to view changes, e.g., by a driver,and/or real-time camera calibration, and for automatic concealment ofartifacts caused by some of the run-time errors. In some embodiments,artifact causing errors are signaled to a user specified control programvia interrupts, which allows the control program to modify GCEparameters in real time to avoid future errors. Further, the GCE mayconceal visual artifacts in the output image caused by some errors byapproximating the missing pixel data with the nearest availableneighboring pixel data.

FIG. 3 is a block diagram illustrating an example of a video processingaccelerator (VPAC) 300 incorporating a GCE 303 in accordance with someembodiments. The VPAC 300, which may be included in a system-on-a-chip(SoC) includes the GCE 303, a scalar component 308, a noise filter (NF)component 310, two vision imaging sub-systems (VISS) 309, a hardwarethread scheduler 302, a configuration component 301, a shared memoryinterconnect 304, local shared memory 305, a direct memory access (DMA)port 306, and a master port 307.

The GCE 303 reads input images via the master port 307 and performsgeometric correction, e.g., geometric distortion correction, perspectivetransformation, and/or rotational video stabilization, on the images togenerate output images as described herein. The output of the GCE 303can be sent to external memory or to other hardware components such asthe scalar component 308 or the noise filter component 310 for furtherpre-processing via local shared memory 305.

The scalar component 308 reads data from shared memory 304 and generatesscaled outputs with various scaling ratios. The output of the scalarcomponent is stored in local shared memory 305 and can be filtered bythe noise filter component 310 or written to external memory.

The noise filter component 310 performs bilateral filtering to removenoise. The output of the noise filter component can be sent to externalmemory from local shared memory 305 or can be further re-sized by thescalar component 308. The local shared memory 305 is used to exchangedata across hardware components such as the GCE 303, the scalarcomponent 308, and the noise filter component 310 as well as to the DMAport 306.

The vision imaging subsystems 309 perform raw data image processing suchas defect pixel correction, lens shading correction, global/localbrightness and contrast enhancement, demosaicing, and color conversion.

The hardware thread scheduler 302 is used for communication among thevarious hardware components of the VPAC 300. The configuration manager301 is used by external configuration software executing on a processorin the SoC to set parameter values of the various hardware components.The VPAC 300 may further include typical hardware inputs such as clock,reset, network, data, and debug signals and hardware outputs such asinterrupt signals.

FIG. 4 is a block diagram of an example GCE 400, e.g., the GCE 303 ofFIG. 3 , in accordance with some embodiments. As is explained in moredetail herein in reference to FIG. 6 , the GCE 400 is configured toreport run-time errors that may occur at various points in the GCEprocessing. Further, for some of the run-time errors, the GCE 400 isconfigured to conceal artifacts in the output frame resulting from theseerrors.

The GCE 400 performs geometric correction operations on blocks of aninput frame to generate corresponding blocks of an output frame. Morespecifically, the output frame may be generated using a single userspecified output block size for the entire output frame or the outputframe may be divided into up to nine regions via user specifiedconfiguration parameters and each region may have a region specificoutput block size also specified by the user. FIG. 5 is an exampleillustrating division of an output frame into nine regions in which eachregion has a different block size. A user supplied control programexecuting on a processor of a system-on-a-chip incorporating the GCE 400supplies the configuration parameter values specifying the number ofregions, the sizes of the regions, and the size of the output block ineach region. Additional information regarding division of output framesinto multiple regions and output block sizes for processing by a GCE maybe found, for example, in United States Patent Publication No.2019/0096041, filed Sep. 25, 2017, which is incorporated by referenceherein. The GCE 400 operates on each region in raster scan order togenerate geometrically corrected output blocks from corresponding blocksin the input frame.

The GCE 400 includes a counter component 402, a transform component 404,a back mapping component 406, a mesh lookup table (LUT) 408, a muxingcomponent 415 configured to select whether to use the output of thetransform component 404 or the back mapping component 406, a buffer 409,an interpolation component 410, a frame buffer interface 411 coupled toexternal memory 401 incorporating a frame buffer for the input frame,and a shared memory interface 414 coupled to an external shared memory413 where the geometrically corrected output frame is stored. A briefdescription of these components is provided herein. Additional detailregarding the operation of examples of such components may be found inthe previously cited U.S. Patent Publication No. 2019/0096041.

The counter component 402 is configured to compute coordinates 403 ofpixel locations in an output block in the output frame for the regionbeing processed. The computation of the coordinates is based on the userspecified size of output blocks in the region, the user specified sizeof the region, and the position of the output block in the raster scanorder processing of the region.

The transform component 404 and the back mapping component 406 areconfigured to generate coordinates 407 of a displaced pixel in the inputframe corresponding to the coordinates in the output block computed bythe counter block 402. The transform component 404 is configured toapply an affine and/or perspective transform to the output block pixelcoordinates to generate perspective warped output block coordinates 405if enabled by the user supplied control program. If application of atransform is not enabled, the transform component block 404 outputs theunaltered coordinates of the output block generated by the countercomponent.

The back mapping component 406 is configured to generate the coordinates407 of the displaced pixel in the input frame corresponding to theoutput block coordinates received from the transform component 404. Thecorresponding coordinates in the input image may be calculated bycombining the received output coordinates with offsets from the usersupplied mesh lookup table (LUT) 408 located based on the receivedoutput block coordinates. The mesh LUT 408, which may also be referredto as an offset table, is a regular grid mapping locations of pixels inthe output frame to corresponding locations in the input frame and isprovided by the user. The mesh LUT 408 defines an offset vector (Δx, Δy)for locations in the output frame. The grid may be fully sampled or downsampled. A fully sampled grid defines an offset vector for each outputpixel, defining exactly where to fetch the input data to compute theoutput pixel. If the grid is subsam pled, bilinear interpolation is usedto interpolate missing offset vectors.

The buffer 409 is configured to receive and store input pixels retrievedfrom the frame buffer in external memory 401 via the frame bufferinterface 411. The input pixels correspond to the pixel coordinatesgenerated by the back mapping component 406 if back mapping is enabledor to pixel coordinates output by the transform component 404 if backmapping is not enabled.

The interpolation component 410 is configured to interpolate input pixelvalues received from the buffer component 409 using either bicubic orbilinear interpolation as specified by the user supplied configurationprogram to generate the value of the output pixels, i.e., the values ofthe output pixels at the coordinates generated by the counter component402. After the interpolation, the geometrically corrected output blockis stored in an output frame buffer in the SL2 shared memory 413 via theSL2 interface 414.

FIG. 6 is an example illustrating the operation of the GCE 400. Forsimplicity of explanation, the example assumes applying a perspectivetransform and back mapping are enabled and the mesh LUT is sub-sampled.For an output block in a region of the output frame, the countercomponent 402 calculates the coordinates of the four corners of theoutput block, and the transform component 404 applies a perspectivetransform 600 to these coordinates to generate perspective warpedcoordinates for the back mapping component 406.

The perspective warped coordinates are used by the transform component404 to compute 602 the corner coordinates in the mesh LUT 408 of a meshLUT block 618 corresponding to the output block. More specifically, thetransform component 404 computes a rectangular bounding box 740 such asthat shown in the example of FIG. 7 for the mesh data to fetch, e.g.,the mesh LUT block 618, such that the bounding box 740 contains meshpoints corresponding the four perspective warped corner coordinates,e.g., corner 711. FIG. 7 shows an example output block 720 and thebounding box 730 of the output block 720 given the perspective warpedcoordinates of the corners of the output block 720. The back mappingcomponent 406 uses bilinear interpolation to up-sample the sub-sampledmesh points 701, 702, 703, 704 to pixel co-ordinate precision. For themesh point bilinear interpolation, the bounding box after perspectivewarp 730 is extended by one column to the right and one row at thebottom to form the rectangular bounding box 740.

If the size of the mesh LUT block 618 is larger than the internalstorage allocated in the buffer 409 for a mesh LUT block and/or anyboundary of the block exceeds the hardware address size, the transformcomponent 404 causes a mesh block overflow event to be reported. Thetransform component 404 will cause this event to be reported once foreach mesh block for which this error occurs along with the left topcorner coordinates of the corresponding output block. This event may bereferred to as mesh_iblk_memovf herein. This run-time error conditioncan cause visible corruption in one or more output blocks. This errormay occur, for example, due to an output block size that is too large,incorrect values of parameters for the affine or perspective transforms,or a too small sub-sampling factor for the mesh LUT.

Referring again to FIG. 6 , the GCE 400 fetches 604 the mesh LUT block618 corresponding to the mesh table bounding block computed by thetransform component 404 and stores the mesh LUT block 618 in the buffer409. The back mapping component 406 then back maps 606 the perspectivewarped corners of the output block computed by the transform component404 to coordinates in the input frame using the mesh LUT block 618 anduses the back mapped corner coordinates to compute 608 a bounding boxfor the input frame block corresponding to the output block. The backmapping component 406 applies additional padding, e.g., one or moreadditional rows and columns of pixels, around the back mappedcoordinates to compute the final coordinates of the input bounding box.The amount and location of the padding depends on the type ofinterpolation to be performed by the interpolation component 410.Additional user defined padding may also be applied in all directions tocompute the final bounding box. The GCE 400 fetches 610 the input frameblock 612 identified by the computed input bounding block and stores theinput frame block 612 in the buffer 409.

If the size of the input frame block 612 is larger than the internalstorage allocated in the buffer 409 for an input frame block and/or anyboundary of the block exceeds the hardware address size, the backmapping component 406 causes a pixel block overflow event to bereported. The back mapping component 406 will cause this event to bereported once for each input block for which the error occurs along withthe left top corner coordinates of the corresponding output block. Thisevent may be referred to as pix_iblk_memovf herein. This run-time errorcondition can cause visible corruption in one or more output blocks.This error may occur, for example, due to an output block size that istoo large.

Once the input data needed to generate the output block, i.e., the meshLUT block 618 and the input frame block 612, is available, the GCE 400performs block processing to generate the pixel values of the outputblock from corresponding geometrically corrected pixels of the inputframe block 612. The counter component 402 computes the coordinates ofeach pixel location in the output block in raster scan order andprovides the coordinates to the transform component 404.

The transform component 404 applies a perspective transform 614 to thesecoordinates to generate perspective warped coordinates for the backmapping component 406. If the values of intermediate variables of anaffine or perspective transform operation exceed what the GCE hardwarecan support, the transform component 404 causes an internal precisionerror event to be reported for the first occurrence of this error ineach frame. This error may occur, for example, due to incorrect valuesof user specified transform coefficients. When such errors occur, thetransform component 404 clips the intermediate variable values to thesize the hardware supports. This event may be referred to as int_szovfherein.

Further, if the perspective warped coordinates are outside theboundaries of the mesh LUT, i.e., outside the frame size for which meshdata is available in the mesh LUT, the transform component 404 clips 616the coordinates to the boundary of the mesh LUT. In addition, thetransform component 404 causes a frame out of bound event to be reportedfor the first occurrence of this error in each frame. This event may bereferred to as ifr_outofbound herein.

Further, if the perspective warped coordinates are outside theboundaries of the mesh LUT block 618, the transform component 404 clips616 the out-of-bounds coordinates to the boundary of the mesh LUT block618. In addition, the transform component 404 causes a mesh block out ofbound event to be reported for the first occurrence of this error ineach frame. This event may be referred to as mesh_iblk_outofboundherein.

The back mapping component 406 back maps 620 the perspective warpedcoordinates of the output pixel location computed by the transformcomponent 404 to coordinates in the input frame block 612 using the meshLUT block 618. Further, if the input frame block coordinates are outsidethe boundaries of the input frame, the back mapping component 406 clips622 the coordinates to the boundary of the input frame. In addition, theback mapping component 406 causes a frame out of bound event to bereported for the first occurrence of this error in each frame. Thisevent may be referred to as ifr_outofbound herein.

Further, if the input block coordinates are outside the boundaries ofthe input frame block 612, the p mapping component 406 clips 622 theout-of-bounds coordinates to the boundary of the input frame block 612.The clipping of the out-of-bounds coordinates has the effect ofconcealing any artifacts in the output block that would otherwise haveoccurred due to this error. In addition, the back mapping component 406causes an input block out of bound event to be reported for the firstoccurrence of this error in each frame along with the left top cornercoordinates of the corresponding output block. This event may bereferred to as pix_iblk_outofbound herein.

The pixel value to be stored at the output block coordinates is theninterpolated 624 by the interpolation component 410 based on thecoordinates provided by the back mapping component. For example, ifbi-cubic interpolation is selected, the output pixel value isinterpolated from the sixteen pixel values in a 4×4 grid around thelocation indicated by the input block coordinates. If bilinearinterpolation is selected, the output pixel value is interpolated fromthe four pixels values in a 2×2 grid around the location indicated bythe input block coordinates.

FIG. 8 is a flow diagram of a method for error handling in a GCE, e.g.,the GCE 400 of FIG. 4 , in accordance with some embodiments. Initially,the GCE receives 800 configuration parameters from a user suppliedcontrol program for performing geometric correction to generate anoutput frame. Examples of such configuration parameters are previouslydescribed herein. The GCE then generates output blocks of the outputframe in accordance with the configuration parameters based on inputblocks of an input frame. Generation of output blocks is previouslydescribed herein. During the generation of the output blocks, the GCEmay detect 804 a run-time error as previously described herein. When arun-time error is detected, the GCE reports 806 an event correspondingto the run-time error to the user supplied control program. Depending onthe particular run-time error, the GCE may also perform correctiveactions appropriate to the error as previously described herein, e.g.,clipping coordinates to boundaries, to conceal potential artifacts inthe output image that would result from the run-time error. Responsiveto the particular run-time error, the user supplied control program maymodify one or more configuration parameters, and the GCE will receive808 the modified configuration parameters for use in generating anotheroutput frame.

FIG. 9 is a high level block diagram of an example multiprocessorsystem-on-a-chip (SoC) 900 that may be configured to perform embodimentsof error handling in a GCE as described herein. In particular, theexample SoC 900 is an embodiment of the TDA4VM SoC available from TexasInstruments, Inc. A high level description of the components of the SoC900 is provided herein. More detailed descriptions of example componentsmay be found in “TDA4VM Jacinto™ Automotive Processors for ADAS andAutonomous Vehicles Silicon Revision 1.0,” Texas Instruments, SPRSP36E,February, 2019, revised December, 2019, pp. 1-311, which is incorporatedby reference herein.

The SoC 900 includes numerous subsystems across different domains suchas one dual-core 64-bit Arm® Cortex®-A72 microprocessor subsystem 904, amicrocontroller unit (MCU) island 906, based on two dual-core Arm®Cortex®-R5F MCUs, four additional dual-core Arm® Cortex®-R5F MCUs 912 inthe main domain, two C66x floating point digital signal processors(DSPs) 908, one C71x floating point, vector DSP 910, that includes adeep-learning matrix multiply accelerator (MMA), and 3D graphicsprocessing unit (GPU) 913. The SoC 900 further includes a memorysubsystem 914 including up to 8 MB of on-chip static random accessmemory (SRAM), an internal DMA engine, a general purpose memorycontroller (GPMC), and an external memory interface (EMIF) module(EMIF). In addition, the SoC 900 includes a capture subsystem 916 withtwo camera streaming interfaces, a vision processing accelerator (VPAC)902 including a GCE, a depth and motion processing accelerator (DMPAC)918, and a video acceleration module 920. The SoC 900 also includes adisplay subsystem 922, an ethernet subsystem 924, a navigator subsystem926, various security accelerators 928, support for system services 930,and a variety of other interfaces 932.

Software instructions implementing a user supplied control program asdescribed herein may be stored in the memory subsystem 914 (e.g., acomputer readable medium) and may execute on one or more programmableprocessors of the SOC 900, e.g., the DSP 910. Further, the GCE in theVPAC 902 may be, for example, an embodiment of the GCE 400 of FIG. 4 .

Other Embodiments

While the disclosure has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be devised whichdo not depart from the scope disclosed herein.

For example, embodiments have been described herein in which cornercoordinates of the output block for which an error occurred are reportedfor some of the error events. In other embodiments, a bounding blockcovering all output blocks in a region corresponding to an error event,i.e., incurring the run-time error corresponding to the error event, maybe reported for some error events, e.g., mesh_iblk_memovf,pix_iblk_memovf, int_szovf, pix_iblk_outofbound, and ifr_outofbound. Insome such embodiments, options are provided such that a user program canchoose to have a bounding block reported for mesh_iblk_memovf,pix_iblk_memovf, and int_szovf or for all five events. In all suchembodiments, after the GCE completes processing of an image, the usersupplied control program can check for such bounding boxes. The usersupplied control program can choose to cause the GCE to execute again onthe area(s) identified by the bounding box(es) with differentparameters, in which case the output of the GCE for the area(s) willreplace the output from the original execution of the GCE. The usersupplied control program can also choose to modify configurationparameters of the GCE for processing the next image rather thanattempting to change the GCE output for the current image.

It is therefore contemplated that the appended claims will cover anysuch modifications of the embodiments as fall within the true scope ofthe disclosure.

What is claimed is:
 1. A method for error handling in a geometriccorrection engine (GCE), the method comprising: receiving configurationparameters by the GCE; generating, by the GCE in accordance with theconfiguration parameters, output blocks of an output frame based oncorresponding blocks of an input frame; detecting, by the GCE, whether arun-time error occurred during the generating; based on the run-timeerror, correcting, by the GCE, a value that has exceeded a boundary suchthat the corrected value is at the boundary; and reporting, by the GCE,an event corresponding to the run-time error.
 2. The method of claim 1,wherein the run-time error can cause artifacts in the output frame. 3.The method of claim 1, wherein reporting further comprises reporting topleft corner coordinates of an output block corresponding to the event.4. The method of claim 1, wherein reporting further comprises reportinga bounding box covering all output blocks in a region of the outputframe incurring the run-time error.
 5. The method of claim 4, furthercomprising receiving, by the GCE, one or more modified parameters,wherein the GCE generates new output blocks for the output blocks in thebounding box in accordance with the one or more modified parameters. 6.The method of claim 1, wherein: the run-time error is a first run-timeerror; the generating of the output blocks includes applying aperspective transform to corner coordinates of an output block togenerate perspective warped corner coordinates and computing a meshlookup table (LUT) block corresponding to the output block based on theperspective warped corner coordinates; and the method further comprisesdetecting whether a second run-time error occurred that is associatedwith a size of the mesh LUT block being larger than an internal storageof the GCE allocated for a mesh LUT block.
 7. The method of claim 6,wherein: the generating of the output blocks includes back mapping theperspective warped corner coordinates to coordinates in the input frameusing the mesh LUT block and computing a bounding box for an input frameblock corresponding to the output block based on the coordinates in theinput frame; and the method further comprises detecting whether a thirdrun-time error occurred that is associated with a size of the inputframe block is larger than an internal storage of the GCE allocated foran input frame block.
 8. The method of claim 1, wherein: the generatingof the output blocks includes applying a perspective transform tocoordinates of a pixel location in an output block to generateperspective warped coordinates; the run-time error is associated with avalue of an intermediate variable of the perspective transform exceedinga size the GCE supports; and the correcting of the value includessetting the value of the intermediate variable to the size the GCEsupports.
 9. The method of claim 1, wherein: the generating of theoutput blocks includes applying a perspective transform to coordinatesof a pixel location in an output block to generate perspective warpedcoordinates; the run-time error is associated with the perspectivewarped coordinates being outside an output frame size for which meshdata is available in a mesh lookup table (LUT) indicated by one of theconfiguration parameters; and the correcting of the value includessetting the perspective warped coordinates to a boundary of the meshLUT.
 10. The method of claim 9, wherein: the run-time error is a firstrun-time error; the method further comprises detecting whether a secondrun-time error occurred that is associated with the perspective warpedcoordinates being outside boundaries of a mesh LUT block correspondingto the output block; and based on the second run-time error, setting theperspective warped coordinates to a boundary of the mesh LUT block. 11.The method of claim 10, wherein: the generating of the output blocksincludes back mapping the perspective warped coordinates to coordinatesin an input frame block corresponding to the output block using the meshLUT block; and the method further comprises detecting whether a thirdrun-time error occurred that is associated with the input frame blockcoordinates being outside boundaries of the input frame; and based onthe third run-time error, setting the input frame block coordinates to aboundary of the input frame.
 12. The method of claim 11, wherein themethod further comprises: detecting whether a fourth run-time erroroccurred that is associated with the input frame block coordinates beingoutside boundaries of the input frame block corresponding to the outputblock; and based on the fourth run-time error, setting the input frameblock coordinates to a boundary of the input frame block.
 13. Asystem-on-a-chip (SoC) comprising: a geometric correction engine (GCE)configured to: receive configuration parameters from a user suppliedcontrol program; generate, in accordance with the configurationparameters, output blocks of an output frame based on correspondinginput blocks of an input frame; detect whether a run-time error occurredassociated with the generating of the output blocks; based on therun-time error, correcting, by the GCE, a value that has exceeded aboundary by setting the value to the boundary; and report an eventcorresponding to the run-time error to the user supplied controlprogram; a memory configured to store software instructions implementingthe user supplied control program for the GCE; and at least oneprocessor coupled to the memory to execute the software instructions.14. The SoC of claim 13, wherein the run-time error can cause artifactsin the output frame.
 15. The SoC of claim 13, wherein the GCE is furtherconfigured to report top left corner coordinates of an output blockcorresponding to the event.
 16. The SoC of claim 13, wherein the GCE isfurther configured to report a bounding box covering all output blocksin a region of the output frame incurring the run-time error.
 17. TheSoC of claim 16, wherein the GCE is further configured to receive one ormore modified parameters, wherein the GCE generates new output blocksfor the output blocks in the bounding box in accordance with the one ormore modified parameters.
 18. The SoC of claim 13, wherein: the run-timeerror is a first run-time error; and the GCE is further configured to:generate the output blocks by applying a perspective transform to cornercoordinates of an output block to generate perspective warped cornercoordinates and computing a mesh lookup table (LUT) block correspondingto the output block based on the perspective warped corner coordinates;and detect whether a second run-time error occurred that is associatedwith a size of the mesh LUT block being larger than internal storage ofthe GCE allocated for a mesh LUT block.
 19. The SoC of claim 18, whereinthe GCE is further configured to: generate the output blocks by backmapping the perspective warped corner coordinates to coordinates in theinput frame using the mesh LUT block and computing a bounding box for aninput frame block corresponding to the output block based on thecoordinates in the input frame; and detect whether a third run-timeerror occurred that is associated with a size of the input frame blockbeing larger than internal storage of the GCE allocated for an inputframe block.
 20. The SoC of claim 13, wherein: the GCE is furtherconfigured to generate the output blocks by applying a perspectivetransform to coordinates of a pixel location in an output block togenerate perspective warped coordinates; the run-time error isassociated with a value of an intermediate variable of the perspectivetransform exceeding a size the GCE supports; and the correcting of thevalue includes setting the value of the intermediate variable to thesize the GCE supports.
 21. The SoC of claim 13, wherein: the GCE isfurther configured to generate the output blocks by applying aperspective transform to coordinates of a pixel location in an outputblock to generate perspective warped coordinates; the run-time error isassociated with the perspective warped coordinates being outside anoutput frame size for which mesh data is available in a mesh lookuptable (LUT) indicated by one of the configuration parameters; and thecorrecting of the value includes setting the perspective warpedcoordinates to a boundary of the mesh LUT.
 22. The SoC of claim 21,wherein: the run-time error is a first run-time error; and the GCE isfurther configured to: detect whether a second run-time error occurredthat is associated with the perspective warped coordinates being outsideboundaries of a mesh LUT block corresponding to the output block; andbased on the second run-time error, set the perspective warpedcoordinates to a boundary of the mesh LUT block.
 23. The SoC of claim22, wherein the GCE is further configured to: generate the output blocksby back mapping the perspective warped coordinates to coordinates in aninput frame block corresponding to the output block using the mesh LUTblock; detect whether a third run-time error occurred that is associatedwith the input frame block coordinates being outside boundaries of theinput frame; and based on the third run-time error, set the input frameblock coordinates to a boundary of the input frame.
 24. The SoC of claim23, wherein the GCE is further configured to: detect whether a fourthrun-time error occurred that is associated with the input frame blockcoordinates being outside boundaries of an input frame blockcorresponding to the output block; and based on the fourth run-timeerror, set the input frame block coordinates to a boundary of the inputframe block.
 25. A geometric correction engine (GCE) comprising: atransform component configured to: apply a perspective transform tocoordinates of corners of an output block of an output frame to generatefirst perspective warped coordinates; compute coordinates of corners ofa mesh look-up table (LUT) block in a mesh LUT using the firstperspective warped coordinates, wherein the mesh LUT block correspondsto the output block; and detect and report a first run-time error when asize of the mesh LUT block is larger than internal storage allocated fora mesh LUT block; and a back mapping component configured to: back mapthe first perspective warped coordinates to coordinates in an inputframe using the mesh LUT block; compute a bounding box for an inputframe block corresponding to the output block based on the coordinatesin the input frame; and detect and report a second run-time error when asize of the input frame block is larger than internal storage of the GCEallocated for an input frame block.
 26. The GCE of claim 25, wherein:the transform component is further configured to: apply the perspectivetransform to coordinates of a pixel location in the output block togenerate second perspective warped coordinates; detect and report athird run-time error when a value of an intermediate variable of theperspective transform exceeds a size the GCE supports, wherein thetransform component clips the value of the intermediate variable to thesize the GCE supports; and detect and report a fourth run-time errorwhen the second perspective warped coordinates are outside an outputframe size for which mesh data is available in the mesh LUT, wherein thetransform component clips the second perspective warped coordinates to aboundary of the mesh LUT; and the back mapping component is furtherconfigured to: back map the second perspective warped coordinates tocoordinates in the input frame block using the mesh LUT block; detectand report a fifth run-time error when the input frame block coordinatesare outside boundaries of the input frame, wherein the back mappingcomponent clips the input frame block coordinates to a boundary of theinput frame; and detect and report a sixth run-time error when the inputframe block coordinates are outside boundaries of the input frame block,wherein the back mapping component clips the input frame blockcoordinates to a boundary of the input frame block.
 27. The GCE of claim26, further comprising an interpolation component configured tointerpolate a value of the pixel location in the output block based onthe input frame block coordinates.
 28. The GCE of claim 26, wherein theback mapping component is further configured to detect and report aseventh run-time error when the second perspective warped coordinatesare outside boundaries of the mesh LUT block, wherein the transformcomponent clips the perspective warped coordinates to a boundary of themesh LUT block.